2 * drivers/power/process.c - Functions for starting/stopping processes on
5 * Originally from swsusp.
11 #include <linux/interrupt.h>
12 #include <linux/oom.h>
13 #include <linux/suspend.h>
14 #include <linux/module.h>
15 #include <linux/syscalls.h>
16 #include <linux/freezer.h>
17 #include <linux/delay.h>
18 #include <linux/workqueue.h>
19 #include <linux/kmod.h>
20 #include <trace/events/power.h>
23 * Timeout for stopping processes
25 unsigned int __read_mostly freeze_timeout_msecs = 20 * MSEC_PER_SEC;
27 static int try_to_freeze_tasks(bool user_only)
29 struct task_struct *g, *p;
30 unsigned long end_time;
33 struct timeval start, end;
35 unsigned int elapsed_msecs;
37 int sleep_usecs = USEC_PER_MSEC;
39 do_gettimeofday(&start);
41 end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
44 freeze_workqueues_begin();
48 read_lock(&tasklist_lock);
49 for_each_process_thread(g, p) {
50 if (p == current || !freeze_task(p))
53 if (!freezer_should_skip(p))
56 read_unlock(&tasklist_lock);
59 wq_busy = freeze_workqueues_busy();
63 if (!todo || time_after(jiffies, end_time))
66 if (pm_wakeup_pending()) {
72 * We need to retry, but first give the freezing tasks some
73 * time to enter the refrigerator. Start with an initial
74 * 1 ms sleep followed by exponential backoff until 8 ms.
76 usleep_range(sleep_usecs / 2, sleep_usecs);
77 if (sleep_usecs < 8 * USEC_PER_MSEC)
81 do_gettimeofday(&end);
82 elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
83 do_div(elapsed_msecs64, NSEC_PER_MSEC);
84 elapsed_msecs = elapsed_msecs64;
88 printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "
89 "(%d tasks refusing to freeze, wq_busy=%d):\n",
90 wakeup ? "aborted" : "failed",
91 elapsed_msecs / 1000, elapsed_msecs % 1000,
92 todo - wq_busy, wq_busy);
95 read_lock(&tasklist_lock);
96 for_each_process_thread(g, p) {
97 if (p != current && !freezer_should_skip(p)
98 && freezing(p) && !frozen(p))
101 read_unlock(&tasklist_lock);
104 printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
105 elapsed_msecs % 1000);
108 return todo ? -EBUSY : 0;
112 * Returns true if all freezable tasks (except for current) are frozen already
114 static bool check_frozen_processes(void)
116 struct task_struct *g, *p;
119 read_lock(&tasklist_lock);
120 for_each_process_thread(g, p) {
121 if (p != current && !freezer_should_skip(p) &&
128 read_unlock(&tasklist_lock);
134 * freeze_processes - Signal user space processes to enter the refrigerator.
135 * The current thread will not be frozen. The same process that calls
136 * freeze_processes must later call thaw_processes.
138 * On success, returns 0. On failure, -errno and system is fully thawed.
140 int freeze_processes(void)
145 error = __usermodehelper_disable(UMH_FREEZING);
149 /* Make sure this task doesn't get frozen */
150 current->flags |= PF_SUSPEND_TASK;
153 atomic_inc(&system_freezing_cnt);
156 printk("Freezing user space processes ... ");
158 oom_kills_saved = oom_kills_count();
159 error = try_to_freeze_tasks(true);
161 __usermodehelper_set_disable_depth(UMH_DISABLED);
162 oom_killer_disable();
165 * There might have been an OOM kill while we were
166 * freezing tasks and the killed task might be still
167 * on the way out so we have to double check for race.
169 if (oom_kills_count() != oom_kills_saved &&
170 !check_frozen_processes()) {
171 __usermodehelper_set_disable_depth(UMH_ENABLED);
172 printk("OOM in progress.");
188 * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
190 * On success, returns 0. On failure, -errno and only the kernel threads are
191 * thawed, so as to give a chance to the caller to do additional cleanups
192 * (if any) before thawing the userspace tasks. So, it is the responsibility
193 * of the caller to thaw the userspace tasks, when the time is right.
195 int freeze_kernel_threads(void)
199 printk("Freezing remaining freezable tasks ... ");
200 pm_nosig_freezing = true;
201 error = try_to_freeze_tasks(false);
209 thaw_kernel_threads();
213 void thaw_processes(void)
215 struct task_struct *g, *p;
216 struct task_struct *curr = current;
218 trace_suspend_resume(TPS("thaw_processes"), 0, true);
220 atomic_dec(&system_freezing_cnt);
222 pm_nosig_freezing = false;
226 printk("Restarting tasks ... ");
228 __usermodehelper_set_disable_depth(UMH_FREEZING);
231 read_lock(&tasklist_lock);
232 for_each_process_thread(g, p) {
233 /* No other threads should have PF_SUSPEND_TASK set */
234 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
237 read_unlock(&tasklist_lock);
239 WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
240 curr->flags &= ~PF_SUSPEND_TASK;
242 usermodehelper_enable();
246 trace_suspend_resume(TPS("thaw_processes"), 0, false);
249 void thaw_kernel_threads(void)
251 struct task_struct *g, *p;
253 pm_nosig_freezing = false;
254 printk("Restarting kernel threads ... ");
258 read_lock(&tasklist_lock);
259 for_each_process_thread(g, p) {
260 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
263 read_unlock(&tasklist_lock);